Underfeed stoker



March 1934- J. w. ARMOUR Er AL 1,950,536

UNDERFEED STQKER Filed Dec. 25, 1931 INVENTOR JAMES W. ARMOUR CARL H. RICH ATTORNEY 1 Patented Mar. 13, 1934 UNITED STATES PATENT UNDERFEED STOKER setts Application December 26, 1931, Serial No. 583,221"

13 Claims.

This invention relates to underfeed stokers, and more particularly to stokers of the multiple retort type having a plurality of trough-like underfeed retorts extending toward an ash dump at the rear of the furnace.

This type of stoker is well adapted to the burning of bituminous coal beneath steam boilers, and has been made in very large sizes for this purpose. It is found however that certain diniculties arise in connection with the construction and operation of such stokers, and particularly those of considerable length. The retorts serve as beams which support a great weight of fuel, and they have to be of very massive construction to withstand the load imposed thereon. As the retorts are made longer, the weight of the fuel and of the retorts themselves becomes so great that it is not practical to use the ordinary cast iron construction which is satisfactory for the shorter stokers. Yet the use of cast iron for the fuel contacting parts is essential because of its heat resisting properties.

It has heretofore been proposed to form the retort sides of cast iron plates mounted upon a framework or beam of structural steel, but this construction is complicated and expensive, and it is difficult to protect the steel members from the heat. Moreover, this prior arrangement is not well adapted to stokers having reciprocating retort sides, since it does not provide for strengthening the stationary retort bottoms which support a considerable part of the fuel bed.

It has furthermore been proposed to utilize a beam extending transversely beneath the retorts intermediate their length. Such a beam must be of considerable size and strength, particularly in wide stokers, and the construction is therefore expensive. Furthermore, this transverse beam obstructs the air chamber beneath the retorts and usually prevents certain of the tuyere blocks from obtaining the requisite supply of air.

It is accordingly one object of the invention to overcome these difiiculties and to provide a simple and inexpensive construction for a multiple retort stoker which is particularly adapted to stokers of considerable length.

It is a further object of the invention to provide a multiple retort stoker in which both the retort sides and the retort bottoms are adequately supported, without utilizing massive cast iron construction.

It is a further object of the invention to provide a simple means for supporting the retorts of a multiple retort stoker without obstructing the air flow to the tuyere blocks.

It is .a further object to provide a multiple retort stoker having reciprocable retort sides which are supported intermediate their length without obstructing the air flow to the tuyere blocks.

Reciprocable retort sides have been utilized heretofore on multiple retort stokers, but in the prior constructions the retort bottoms have been supported at their lower ends on the retort sides. This has considerably increased the frictional resistance to reciprocation, as well as the power required to operate the stoker, and the wear on the moving parts. Moreover, the retort sides at their upper ends have heretofore been supported on the ends of horizontally slidable cylindrical rods which project beyond their guide bearings, so that the weight has caused the rods to bind in their bearings with resultant excess friction and wear.

It is accordingly a further object of the invention to provide a multiple retort stoker having reciprocable retort sides which may be operated freely with a minimum power consumption.

It is a further object to provide a multiple retort stoker which is so constructed and arranged that the weight of each retort bottom with its superimposed mass of fuel is supported independently of the reciprocable retort sides.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicatelike parts:

Fig. 1 is a side elevation of a multiple retort Stoker, the parts within the furnace being shown in section on the line 1-1 of Fig. 3;

Fig. 2 is a section on the line 2-2 of Fig. 3,

certain parts being removed for clearness of illustration; and

Fig. 3 is an enlarged section on the line 3-3 of Fig. 1.

The embodiment illustrated comprises a furnace having a front wall 10 and a rear wall 11. A fuel hopper 12 is mounted adjacent to the front wall 10 and this hopper is arranged to deliver fuel to a series of horizontal cylindrical ram casings 14. A reciprocable ram (not shown) is mounted within the each ram casing, and a rotatable crankshaft 15 serves tooperate the rams. The crankshaft is driven from a gear reduction mechanism 16, as is common in the art.

A plurality of parallel underfeed retorts extoo and wear.

tend rearwardly from the front wall of the furnace, each retort comprising a bottom plate 17 and side bars 18 forming the retort side walls. Tuyere blocks 19 are mounted in step-like formation on the downwardly and rearwardly sloping top edges of the side bars, and these blocks serve to deliver air to the fuel bed for combustion. Air is supplied to the tuyere blocks from the large air chamber 20 beneath the retorts. A suitable fan (not shown) may be used to maintain the pressure in chamber 20. An overfeed grate 22 is supported on the side bars beyond the rear ends of the retorts, and a damper 23 .is provided to control the air flow from the chamber 2'0 to this grate. A dump plate 24 is pivotally supported at the rear of the overfeed grate, and is held in a desired position of adjustment by means of a link 26, an arm 27, and a horizontal rotatable dump shaft 28. The overfeed grate 22 and the dump plate 24 are preferably each made in sections, with one section to each side bar 18, as disclosed in the patent to Riley No. 1,322,822.

The side bars 18 are arranged to be reciprocated to break up the fuel bed and move it toward the rear, and for this purpose each side bar is supported at its rear end on a shoe 30 which slides on the fiat upper surface of a base plate 31. This base plate rests on a pair of horizontal I-beams 32. The shoe 30 is pivoted to the side bar, and is thereforeself-aligning. Each side bar is driven at its front end by means of a horizontal drive rod 34 which is slidable within a guide bearing 35 formed on the ram casing 14. Each drive rod is connected to the wrist pin 36 of the ram by means of a lost motion connection 38 of well known construction. The drive rod is fastened to the side bar by means of a .pin 39 and a pair of eye-bolts 40.

It has been the practice previously in stokers of this type to support the weight of the side bars at the front by means of the drive rods. Since these rods necessarily project rearwardly beyond their guide bearings, the load has caused the rods to bind, resulting in excessive friction We have overcome this difficulty by providing a supporting means. for the side bar which is independent of the driving means. In the embodiment illustrated this comprises a horizontal channel beam 42 extending transversely beneath the side bars and supported on pipe columns 43. The channel beam is arranged with its flanges at the bottom, and a plate 44 (Fig. 2) is mounted on the channel beam beneath each side bar. A self-aligning shoe 46 is pivoted to the front end of each side bar, and is 'slidably supported on one of the plates 44. With this construction. the guide rods have no weight to support, and they will therefore slide freely in their bearings.

In prior stokers of this type, the retort bottoms have been supported at their lower ends on the side bars, thus adding considerably to the load on the lower side bar shoes, and increasing the friction, wear, and power consumption. In the embodiment illustrated we have avoided these disadvantages by supporting the weight of each retort bottom, with its superimposed load of fuel, independently of the adjacent side bars. For this purpose we have provided a beam 48, preferably an I-beam of structural steel, located beneath each retort bottom plate 17 and extending longitudinally thereof. The beams 48 are supported at the front by the transverse channel beam 42, and at the rear by the base plate 31.

" They are preferably not fastened to the base plate, but merely rest thereon, so that they may slide as the various parts expand or contract with changes in temperature. The bottom plates 17 may be formed of cast iron, and they are preferably supported on the beams 48 by means of bosses or otherwise to provide a space 49. This helps to keep the beams cool by allowing air to circulate over their top surfaces and by minimizing the direct conduction of heat from the retort bottoms to the beams.

In stokers of considerable length we preferably form the side bars 18 in two parts, as shown particularly in Fig. 2, thereby reducing the size of the individual pieces which must be handled at assembly. The front and rear parts of each side bar are joined together by means of a pin or bolt 51 which extends vertically through a lug '52 on the rear member and a similar lug 53 on the front member. Each side bar is supported intermediate its length and preferably close to the joint by means of the adjacent beam 48. In the preferred construction illustrated, we have cut away a portion of the lower flange of the I-beam 48 and fastened an angle 55 to each side of the web of the beam. One leg of each angleprojects laterally from the beam to form a shelf located in a horizontal plane, and the angles are braced at each end by a small vertical plate 56. These various parts are preferably formed of steel and firmly welded together. A wear plate 57 of suitable material, such as cast iron, is mounted on the upper surface of the horizontal leg of each angle, and this plate slidably supports a shoe 58, which in turn supports the side bar 18. The shoe 58 is shaped to fit a semi-circular lug 59 formed integral with the side bar, whereby the shoe may rock on the lug and align itself with the plate 57. The pin 51 fits rather loosely in the lugs 52 and 53, so that the joint is slightly flexible and the shoe 58 may carry the load. With this construction, each side bar provides two short beams instead of a single long beam, and hence can be made comparatively light and inexpensive. The intermediate support does not obstruct the flow of air to the 'tuyere blocks 19, since an ample space is provided between the angles 55 and this space is located directly beneath the tuyere blocks, as shown in Fig. 3.

The operation of the invention, in respect to the feeding "and burning of the fuel, is substantially the same as that of prior stokers of the well-known Riley type. The retorts are supplied with fuel from the hopper 12 by means of reciprocating rams driven by the crankshaft 15, and the side bars 18 are 'reciprocated by the lost motion mechanism 38. The side bars impart motion to the tuyere blocks 19, overfeed grate sections 22, and dump plates 24, thus feeding the fuel rearwardly as it is being burned by means of air supplied from the air chamber 20. Since the weight of the retort bottoms with their superimposed load of fuel is carried by the beams 48 independently of the side bars 18, the latter may be operated much more freely. The shoes 46 relieve the drive rods 34 from any weight supporting function and thus overcome the tendency 'of these parts to bind in previous arrangements. By supporting the side bars intermediate their length from the beams 48, we are able to avoid the necessity for massive construction, thereby reducing the weight and cost of the entire stoker.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An underfeed stoker comprising stationary bottom plates and reciprocable side walls forming a plurality of parallel retorts, and a beam extending longitudinally beneath each bottom plate, said beams serving to support the bottom plates independently of the retort side walls.

2. An underfeed stoker comprising stationary bottom plates and reciprocable side walls forming a plurality of parallel retorts, a beam extending longitudinally beneath each bottom plate,said beams serving to support the bottom plates independently of the retort side walls, means to support one end of each beam rigidly, and means to support the other end of each beam slidably.

3. An underfeed stoker comprising bottom plates and side walls forming a plurality of parallel retorts, and a beam extending longitudinally beneath each bottom plate, said beams serving to support the weight of the bottom plates and the fuel carried by the bottom plates.

d. An underfeed stoker comprising bottom plates and side walls forming 'a plurality of parallel retorts, and a beam extending longitudinally beneath each bottom plate, said beams serving to support the weight of the bottom plates and the fuel carried by the bottom plates, and the beams being spaced from the bottom plates to allow air to circulate over the tops of the beams.

5. An underfeed Stoker comprising a plurality of parallel retorts having side walls, and a beam extending longitudinally beneath the center of each retort, the beams serving to support the side Walls intermediate the length of the side walls.

6. An underfeed stoker comprising a plurality of parallel retorts having side walls, each side wall including a front and a rear portion joined together, and a beam extending longitudinally beneath the center of each retort, the beams serving to support the side Walls near the joints between the front and rear portions thereof.

'7. An under-feed stoker comprising bottom plates and side walls forming a plurality of parallel retorts, each retort side wall including a front and a rear portion joined together, and a beam extending longitudinally beneath the center of each bottom plate, the beams serving to support the bottom plates and the side walls near the joints between the front and rear portions thereof.

8. An underfeed stoker comprising stationary bottom plates and reciprocable side walls forming a plurality of parallel retorts, each retort side wall including a front and a rear portion joined together, a beam extending longitudinally beneath the center of each bottom plate and serving to support the weight thereof, and means on the beams serving to slidably support the retort side walls near the joints between the front and rear portions thereof.

9. An underfeed stoker comprising stationary bottom plates and reciprocable side walls forming a plurality of parallel retorts, each retort side wall including a front and a rear portion joined together, a beam extending longitudinally beneath the center of each bottom plate and serving to support the weight thereof, a shelf projecting laterally from each beam, and a shoe slidable on each shelf, each shoe serving to support one of said side walls near the joint therein.

10. An underfeed stoker comprising a plurality of parallel retorts having reciprocable side walls, a slidable drive rod connected to the front end of each side wall, guide bearings for the drive rods, and means to slidably support each side wall independently of the drive rods.

11. An underfeed stoker comprising a plurality of parallel retorts having stationary bottom plates and reciprocable side walls, a slidable drive rod connected to the front end of each side wall, guide bearings for the drive rods, a rotatable crankshaft, a lost motion connection between the crankshaft and each drive rod, and means to slidably support each side wall independently of the drive rods.

12. An underfeed stoker comprising a plurality of parallel retorts having reciprocable side walls, means to feed fuel into the front ends of'the retorts, a self-aligning shoe at the front end of each side wall, a self-aligning shoe at the rear end of each side wall, means to slidably support each shoe, and means to reciprocate the side 

